The invention relates to a solder ball bounding (SBB) machine and method used in a magnetic head assembly process of HGA production for hard disk drives.
U.S. Pat. No. 5,828,031 entitled xe2x80x9cHead Transducer to Suspension Lead Termination by Solder Ball Place/Reflowxe2x80x9d issued to Surya Pattanaik on Oct. 27, 1998 discloses a method for forming electrical solder connection between a thin film magnetic head transducer and the conductors in an integrated suspension after the head has been mechanically attached to a suspension. A solder ball is placed between the head and conductor termination pads. A focused laser beam is used to produce solder reflow. The resulting solder connection has a very fine grain structure and includes a pair of extremely thin layers of intermedallic compounds in the regions where the solder connection abuts the head and conductor termination pads.
FIG. 1 shows a conventional SBB (solder ball bounding) bond head. As shown in FIG. 1, the SBB bond head has a capillary 2 on its laser head 1 through which the laser beam and the solder ball 3 get to the bump 4 desired. When the laser is turned on, the solder ball 3 will be melt on the bump and the welding finished.
FIG. 2: shows a top view of a head area of an HGA (head gimbal assembly). As shown in FIG. 2, the HGA comprises a slider 24 and a suspension 21 which has a flexure 22 and a flex cable 26 thereon. There are some traces 23 on the flex cable 26 as a signal channel. And there are some bump pads 27 on the slider 24. Usually the slider 24 is bounded on a tongue area 28 of the flexure 22, and is well alignment to a pad 25 of the trace 23 of the flex cable 26.
To derive a signal from the slider 24, it is needed to connect the bump pad 27 of the slider 24 to the bump pad 25 of the trace 23 by an SBB or other bonding method.
A conventional bonding method for an HGA comprises steps as follows:
1. mounting a flex cable 26 on a suspension 21;
2. mounting a slider 24 on the suspension 21;
3. loading the suspension 21 to a fixture 33 in FIG. 3;
4. connecting a pad 25 of a trace 23 with a slider pad 27 on the suspension 21 by an SBB or GBB (gold ball bonding) bonding method; and
5. taking the HGA from the fixture 33, then loading another suspension to the fixture 33, repeating steps 1-4 for bonding a next HGA.
There are three problems in a conventional bonding process by means of a conventional bonding machine as shown in FIG. 3:
1. In order to fix a suspension 21 and a slider 24 in the bonding process, two clamps 31 and 32 as well as a fixture 33 are provided. Consequently, it will be possible to cause damage to the suspension 21.
2. Since the SBB is a kind of heating process by laser power, it is likely to produce a internal stress in the flexure made of metal when bonding a slider to a flexure, which will cause a suspension static pitch/roll change.
3. Since bonding is made at an HGA level, only one HGA can be bonded every time. Therefore, the mass production is difficult, and the efficiency of production is very low.
In order to overcome the above-mentioned drawbacks, it is necessary to change the bonding process from an HGA level to a flex cable level and to add a flex cable sheet convey system to a bonding machine.
Therefore, one object of the present invention is to provide an SBB machine used in a magnetic head assembly process of HGA production.
Another object of the present invention is to provide an SBB method by means of the machine.
In one aspect of the present invention, an SBB machine comprises a laser head with a focus system, a monitor with a camera positioning system and a flex cable sheet station with a conveyer system. The laser head can be controlled from the monitor to move vertically and horizontally by the camera positioning system, and the conveyer belt of the transport system can be controlled to move step by step.
In another aspect of the present invention, A SBB bonding method for an HGA by means of the SBB machine according to the present invention comprises steps:
a) making a flex cable trace pattern on a flex cable sheet by etching or the like;
b) bonding sliders the number of which corresponds to that of the flex cables on the flex cable sheet by SBB or the like, with precise alignment to trace pads one by one;
c) cutting the flex cable provided with the sliders from the flex cable sheet;
d) mounting the flex cable provided with the sliders onto a suspension by epoxy or the like, and finishing an HGA.